JP2019138673A - Rechargeable battery state detector and rechargeable battery state detection method - Google Patents

Abstract

To estimate a polarization voltage with discretionary timing.SOLUTION: The present invention comprises: discharge means (discharge circuit 15) for causing a rechargeable battery to be pulse discharged; measurement means (voltage sensor 11, current sensor 12) for measuring a voltage value and a current value at the time of or before and after a pulse discharge by the discharge means; first calculation means (control unit 10) for calculating the value of a prescribed circuit element constituting an equivalent circuit of the rechargeable battery by a first calculation method on the basis of the measured voltage and current values; second calculation means (control unit 10) for calculating the value of the prescribed circuit element constituting the equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method on the basis of the measured voltage and current values; and calculation means (control unit 10) for calculating the polarization voltage of the rechargeable battery on the basis of a difference or ratio between the values of the circuit measured by the first and second calculation means and a value obtained by applying the values of the equivalent circuit to a prescribed function.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rechargeable battery state detection device and a rechargeable battery state detection method.

  As a technique for detecting the polarization voltage of a rechargeable battery, for example, there is a technique disclosed in Patent Document 1.

  In the technique disclosed in Patent Document 1, the voltage change due to the influence of polarization after the end of charging / discharging varies greatly depending on the charging / discharging history immediately before the end of charging / discharging. Since there is a predetermined correlation with the voltage correction value for obtaining the stable voltage, the voltage correction value is estimated with high accuracy using this correlation. The stable voltage can be obtained with high accuracy from the estimated voltage correction value, and the state can be detected by estimating the charging rate.

JP 2010-014636 A

  By the way, in the technique disclosed in Patent Document 1, since the voltage after the completion of charging / discharging is used, there is a problem that the opportunity for estimating the polarization voltage is limited. In addition, since the polarization voltage changes with time, there is a problem in that the estimation accuracy at the time when the time has elapsed from the estimation deteriorates.

  The present invention has been made in view of the situation as described above, and is capable of estimating a polarization voltage at an arbitrary timing and capable of suppressing a decrease in estimation accuracy even when time elapses from the estimation. It is another object of the present invention to provide a rechargeable battery state detection method.

In order to solve the above-described problems, the present invention provides a rechargeable battery state detection device for detecting a state of a rechargeable battery, a discharge unit that pulse-discharges the rechargeable battery, and a pulse discharge by the discharge unit or the Measuring means for measuring the voltage value and current value before and after, and the value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by the first calculation method based on the voltage value and current value measured by the measuring means And a predetermined circuit that constitutes an equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured by the measurement unit. Second calculation means for calculating the value of the element, and the difference, ratio, or circuit of the values of the circuit elements calculated by the first calculation means and the second calculation means Characterized in that it has a calculation means for calculating a polarization voltage of the rechargeable battery based on the value of the unit to a value obtained by applying a predetermined function, a.
According to such a configuration, the polarization voltage can be estimated at an arbitrary timing, and a decrease in estimation accuracy can be suppressed even when time elapses from the estimation.

Further, the present invention is characterized in that the circuit element to be calculated by the first calculation means and the second calculation means is a reaction resistance or a charge transfer resistance.
According to such a configuration, it is possible to further increase the estimation accuracy by using a circuit element having a high correlation with the polarization voltage.

In the present invention, the first calculation means and the second calculation means are: (1) dividing a voltage value during discharge when the rechargeable battery is discharged by a rectangular pulse having a pulse width T1 by a current value. The value obtained by subtracting the value obtained by dividing the voltage value during discharge by the current value when discharging with a rectangular pulse having a pulse width of T2 (<T1) from the obtained value is the value of the reaction resistance. (2) After correction in which the voltage value and current value during discharge when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 are corrected by the voltage value and current value before and after the discharge, respectively. From the value obtained by dividing the voltage value by the corrected current value, the voltage value and current value during and after the discharge when discharging with a rectangular pulse having a pulse width of T2 (<T1) are obtained. By it A calculation method in which a value obtained by subtracting a value obtained by dividing the corrected voltage value by the corrected current value is a reaction resistance value; (3) discharging when the rechargeable battery is pulse-discharged Fitting a predetermined formula including reaction resistance, conductor resistance, and liquid resistance as coefficients by multiple values obtained by dividing the voltage drop value during discharge from the current value before the start, and the value of the reaction resistance from the coefficient value And any two of the calculation methods (1) to (3) are used.
According to such a configuration, the polarization voltage can be accurately obtained by simple calculation.

Further, the present invention is characterized in that the first calculation means and the second calculation means use the calculation method (1) and the calculation method (2), respectively.
According to such a configuration, the polarization voltage can be obtained with higher accuracy.

In the present invention, the first calculation means and the second calculation means may discharge the rechargeable battery with a rectangular pulse having a pulse width T1 in the calculation method (1) and the calculation method (2). From the value obtained by dividing the voltage value during discharge when divided by the current value, the voltage value during discharge when divided by a rectangular pulse with a pulse width of T2 (<T1) is divided by the current value. Instead of the obtained value, the value of the reaction resistance is obtained by subtracting the value of the conductor resistance / liquid resistance obtained by the calculation method of (3).
According to such a configuration, the value of the reaction resistance can be obtained with high accuracy.

According to the present invention, the value of the reaction resistance obtained by the first calculation means and the second calculation means is determined based on at least one of a temperature, a charging rate (SOC), and an open circuit voltage (OCV) as a predetermined reference. It is characterized by correcting to a value in the state.
According to such a configuration, the polarization voltage can be obtained with high accuracy regardless of the temperature, the charging rate, and the open circuit voltage.

The present invention also relates to a rechargeable battery state detection method for detecting a state of a rechargeable battery, a discharge step for pulse discharging the rechargeable battery, and a voltage value and a current before or after the pulse discharge in the discharge step. A measurement step for measuring a value, and a first calculation for calculating a value of a predetermined circuit element constituting an equivalent circuit of the rechargeable battery by a first calculation method based on the voltage value and the current value measured in the measurement step And a predetermined circuit element constituting a value of an equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured in the measurement step. A difference between the second calculation step and the value of the circuit element calculated in the first calculation step and the second calculation step; Rate, or characterized by having an a calculation step of calculating a polarization voltage of the rechargeable battery based on the values of circuit element values obtained by applying a predetermined function.
According to such a method, the polarization voltage can be estimated at an arbitrary timing, and a decrease in estimation accuracy can be suppressed even when time elapses from the estimation.

  According to the present invention, there is provided a rechargeable battery state detection device and a rechargeable battery state detection method capable of estimating a polarization voltage at an arbitrary timing and suppressing a decrease in estimation accuracy even when time has elapsed since the estimation. It becomes possible to provide.

It is a figure which shows the structural example of the rechargeable battery state detection apparatus which concerns on embodiment of this invention. It is a block diagram which shows the detailed structural example of the control part of FIG. It is a figure which shows the aspect of the measurement of the voltage and electric current at the time of pulse discharge. It is a figure which shows the relationship between SOC change at the time of charge, and polarization voltage. It is a flowchart for demonstrating an example of the process performed in embodiment of this invention. It is a figure which shows the result of the fitting with respect to the several rechargeable battery of a different size. It is a figure which shows the relationship between Rct1_2-Rct1_1 and SOC variation | change_quantity at the time of charge before Rct measurement. It is a figure which shows the relationship between Rct1_2 / Rct1_1 and SOC variation | change_quantity at the time of charge before Rct measurement. It is a figure which shows the relationship between (Rct1_2-Rct1_1) -Rohm and SOC variation | change_quantity at the time of charge before Rct measurement. It is a figure which shows the relationship between Rct1_3 / Rct1_1 and SOC variation | change_quantity at the time of charge before Rct measurement. It is a figure which shows the relationship between Ratio_Rct1_1, Ratio_Rct1_3 and SOC variation | change_quantity at the time of charge before Rct measurement. It is a figure which shows the relationship between (DELTA) Ratio_Rct1_1 and SOC variation | change_quantity at the time of charge before Rct measurement.

  Next, an embodiment of the present invention will be described.

(A) Description of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a rechargeable battery state detection device according to an embodiment of the present invention. In this figure, the rechargeable battery state detection device 1 mainly includes a control unit 10, a voltage sensor 11, a current sensor 12, a temperature sensor 13, and a discharge circuit 15, and detects the state of the rechargeable battery 14. To do. Note that the control unit 10, the voltage sensor 11, the current sensor 12, the temperature sensor 13, and the discharge circuit 15 are not separately configured, and a part or all of them may be combined.

  Here, the control unit 10 refers to the outputs from the voltage sensor 11, the current sensor 12, and the temperature sensor 13, detects the state of the rechargeable battery 14, and controls the power generation voltage of the alternator 16 to perform charging. The charge state of the possible battery 14 is controlled. The voltage sensor 11 detects the terminal voltage of the rechargeable battery 14 and notifies the control unit 10 of it. The current sensor 12 detects the current flowing through the rechargeable battery 14 and notifies the control unit 10 of the current. The temperature sensor 13 detects the electrolyte solution of the rechargeable battery 14 or the temperature around the rechargeable battery 14 and notifies the control unit 10 of the detected temperature. Note that the control unit 10 does not control the charging state of the rechargeable battery 14 by controlling the power generation voltage of the alternator 16, but for example, an unillustrated ECU (Electric Control Unit) controls the charging state. Good.

  The rechargeable battery 14 is composed of a rechargeable battery having an electrolyte, such as a lead storage battery, a nickel cadmium battery, or a nickel metal hydride battery. The rechargeable battery 14 is charged by the alternator 16 and drives the starter motor 18 to start the engine. At the same time, power is supplied to the load 19. The rechargeable battery 14 is configured by connecting a plurality of cells in series.

  The discharge circuit 15 includes, for example, a semiconductor switch and a resistance element connected in series, and discharges the rechargeable battery 14 with a predetermined current by turning on / off the semiconductor switch according to the control of the control unit 10. .

  The alternator 16 is driven by the engine 17 to generate AC power, convert it into DC power by a rectifier circuit, and charge the rechargeable battery 14. The alternator 16 is controlled by the control unit 10 and can adjust the generated voltage.

  The engine 17 is constituted by, for example, a reciprocating engine such as a gasoline engine and a diesel engine, a rotary engine, or the like, and is started by a starter motor 18 to drive driving wheels through a transmission to provide propulsive force to the vehicle. To generate electric power. The starter motor 18 is constituted by, for example, a DC motor, and generates a rotational force by the electric power supplied from the rechargeable battery 14 to start the engine 17. The load 19 is configured by, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio, a car navigation, and the like, and operates with electric power supplied from the rechargeable battery 14. In the example of FIG. 1, only the engine 17 outputs the driving force. However, for example, a hybrid vehicle including an electric motor that assists the engine 17 may be used. In the case of a hybrid vehicle, the rechargeable battery 14 activates a high-pressure system (system that drives an electric motor) constituted by a lithium battery or the like, and the high-pressure system starts the engine 17.

  FIG. 2 is a diagram illustrating a detailed configuration example of the control unit 10 illustrated in FIG. 1. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, an I / F (Interface) 10e, A bus 10f is provided. Here, the CPU 10a controls each unit based on the program 10ba stored in the ROM 10b. The ROM 10b is configured by a semiconductor memory or the like, and stores a program 10ba or the like. The RAM 10c is configured by a semiconductor memory or the like, and stores data generated when the program 10ba is executed and data 10ca such as a table to be described later. The communication unit 10d communicates with an upper device such as an ECU (Electronic Control Unit) and notifies the detected information or control information to the upper device. The I / F 10e converts the signals supplied from the voltage sensor 11, the current sensor 12, and the temperature sensor 13 into digital signals and takes them in, and supplies drive current to the discharge circuit 15, the alternator 16, the starter motor 18, and the like. Supply them to control them. The bus 10f is a signal line group for mutually connecting the CPU 10a, the ROM 10b, the RAM 10c, the communication unit 10d, and the I / F 10e so that information can be exchanged between them.

(B) Description of Operation of the Embodiment of the Present Invention Next, the operation of the embodiment of the present invention will be described. In the following, the operation of the embodiment of the present invention will be described, and then the processing of a flowchart for realizing such operation will be described with reference to FIG.

  First, the operation of the embodiment of the present invention will be described. First, the CPU 10a of the control unit 10 controls the discharging circuit 15 to discharge the rechargeable battery 14 at least once by a rectangular wave-shaped pulse as shown in the lower side of FIG. Note that the width of the rectangular wave is, for example, 10 ms or more. In FIG. 3, the lower diagram shows current, and a constant current flows during pulse discharge. Moreover, the upper side shows a voltage, and during pulse discharge, the voltage decreases with time.

  At this time, as shown in FIG. 3, the CPU 10 a sets the rechargeable battery 14 at a predetermined sampling interval t_smp for a predetermined time before the pulse discharge, during the pulse discharge, and for a predetermined time after the pulse discharge. The voltage and current are measured (sampled) by the voltage sensor 11 and the current sensor 12.

  As a result, Vb (tn) (tn = tb1 to tbN) and Ib (tn) (tn = tb1 to tbN) are obtained as the voltage and current before the pulse discharge, and V (tn) as the voltage and current during the pulse discharge. (Tn = t1 to tN) and I (tn) (tn = t1 to tN) are obtained, and Va (tn) (tn = ta1 to taN) and Ia (tn) (tn = ta1-taN) are obtained.

  Next, the CPU 10a calculates the voltage difference value V_diff before and after the pulse discharge and the current difference value I_diff by the following equations (1) and (2).

・・・（１）

... (1)

・・・（２）

... (2)

  Next, the CPU 10a corrects the voltage V (tn) and the current I (tn) during pulse discharge based on the following equations (3) and (4).

・・・（３）

... (3)

・・・（４）

... (4)

  The CPU 10a calculates the internal impedance Z of the rechargeable battery 14 by the following equation (5) using the voltage V (tn) and the current I (tn) corrected by the equations (3) and (4).

・・・（５）

... (5)

  Next, the CPU 10a controls the discharge circuit 15 to discharge the rechargeable battery 14 at least once by a rectangular wave pulse wave as shown in FIG. 3, for example. At this time, the width of the rectangular wave is, for example, 3 ms or less. The CPU 10a supplies the voltage and current of the rechargeable battery 14 to the voltage sensor 11 and the current sensor at a predetermined sampling interval t_smp for a predetermined time before the pulse discharge, during the pulse discharge, and for a predetermined time after the pulse discharge. As in the case described above, Vb (tn) (tn = tb1 to tbN) and Ib (tn) (tn = tb1 to tbN) are obtained as the voltage and current before the pulse discharge. V (tn) (tn = t1 to tN) and I (tn) (tn = t1 to tN) are obtained as the voltage and current, and Va (tn) (tn = ta1 to taN) is obtained as the voltage and current after the pulse discharge. ) And Ia (tn) (tn = ta1 to taN).

  Next, the CPU 10a calculates the voltage difference value V_diff and the current difference value I_diff before and after the pulse discharge according to the above-described equations (1) and (2). Then, the CPU 10a calculates the internal impedance Z of the rechargeable battery 14 by the above-described equation (5) using the voltage V (tn) and the current I (tn) corrected by the equations (3) and (4). The internal impedance Z is Rohm_1 as a conductor resistance and a liquid resistance (hereinafter referred to as “conductor resistance / liquid resistance”).

  Then, the CPU 10a obtains a reaction resistance (or charge transfer resistance) Rct1_1 by subtracting the conductor resistance / liquid resistance Rohm_1 from the internal impedance Z measured at 10 ms or more as the width of the rectangular wave. Note that the reaction resistance Rct1_1 may be obtained by subtracting Rohm_3 calculated by the equation (9) described later from the internal impedance Z measured as the width of the rectangular wave at 10 ms or more.

  Next, the CPU 10a sets the width of the rectangular wave to 10 ms or more by the same method as described above, and V (tn) (tn = t1 to tN) and I (tn) as voltage and current during pulse discharge. (Tn = t1 to tN) is obtained. Subsequently, the CPU 10a calculates the internal impedance Z when the width of the rectangular wave is 10 ms or more according to the equation (5) without performing the correction according to the equations (1) to (4). Next, the CPU 10a sets the width of the rectangular wave to 3 ms or less by the same method as described above, and V (tn) (tn = t1 to tN) and I (tn) as voltage and current during pulse discharge. (Tn = t1 to tN) is obtained. Subsequently, the CPU 10a calculates the internal impedance Z when the width of the rectangular wave is 3 ms or less according to the equation (5) without performing the correction according to the equations (1) to (4), and calculates the internal impedance Z. Conductor resistance / liquid resistance Rohm_2. Then, the resistance Rct1_2 is obtained by subtracting the conductor resistance / liquid resistance Rohm_2 from the internal impedance Z measured at 10 ms or more as the width of the rectangular wave. Note that the reaction resistance Rct1_2 may be obtained by subtracting Rohm_3 calculated by the equation (9) described later from the internal impedance Z measured as the width of the rectangular wave at 10 ms or more.

  Next, the CPU 10a corrects the two types of reaction resistance Rct1_1 and reaction resistance Rct1_2 obtained by the above calculation to values at a reference temperature (for example, 25 ° C.) and a reference SOC (for example, 100%). Subsequently, the CPU 10a applies the two types of reaction resistance Rct1_1 and reaction resistance Rct1_2 to the following equation (6) to obtain ΔRct1.

  ΔRct1 = Rct1_2−Rct1_1 (6)

  Here, since there is a correlation between the reaction resistance Rct and the charging rate SOC, the CPU 10a applies ΔRct1 obtained by the equation (6) to the following equation (7), which is a change amount of the SOC. ΔSOC is calculated. Note that i () is a predetermined function with ΔRct1 as a variable, and can be obtained by actual measurement, for example.

  ΔSOC = i (ΔRct1) (7)

  Next, the CPU 10a calculates the polarization voltage Vp from ΔSOC obtained by the equation (7) based on the following equation (8). Note that j () is a predetermined function having ΔSOC as a variable, and can be obtained by actual measurement, for example.

  Vp = j (ΔSOC) (8)

  That is, since there is a correlation between ΔSOC and the polarization voltage Vp as shown in FIG. 4, the polarization voltage Vp can be obtained by using the function j () corresponding to these correlations. . In FIG. 4, the horizontal axis indicates ΔSOC, and the vertical axis indicates the polarization voltage.

  As described above, according to the embodiment of the present invention, the charging rate variation ΔSOC and the polarization voltage Vp are obtained by pulse discharge. ΔSOC and Vp can be determined.

  Further, using the estimated polarization voltage, the open circuit voltage (the voltage when the terminal of the rechargeable battery 14 is opened (OCV)) is corrected, and the SOC is estimated from the corrected open circuit voltage OCV. Thus, the estimation accuracy of the SOC can be improved. Moreover, when calculating the value of the circuit element which comprises the equivalent circuit model of the rechargeable battery 14, the value of a circuit element can be calculated | required correctly by correct | amending using the estimated polarization voltage.

  In the above embodiment, two types of reaction resistances Rct1_1 and reaction resistance Rct1_2 are obtained by individual pulse discharges, but may be obtained by the same pulse discharges.

  Next, details of processing executed in the control unit 10 shown in FIG. 2 will be described with reference to FIG. When the process shown in FIG. 5 is started, the following steps are executed.

  In step S10, the CPU 10a of the control unit 10 determines whether or not the vehicle on which the rechargeable battery 14 is mounted is stopped (a state where the engine 17 is stopped and the driver gets off), and is stopped. Is determined (step S10: Y), the process proceeds to step S11. Otherwise (step S10: N), the process ends. For example, when the vehicle is parked in the parking lot, the engine 17 is stopped, the driver gets off, and a predetermined time has elapsed, it is determined as Y, and the process proceeds to step S11.

  In step S11, the CPU 10a sets the pulse width of the pulse discharge to T1. For example, T1 is set to a predetermined value of 10 ms or more. At this time, the measurement time before and after the pulse discharge is also set. Note that 10 ms is an example, and other values may be used.

  In step S12, the CPU 10a controls the discharge circuit 15 via the I / F 10e to discharge the rechargeable battery 14 at least once by a pulse waveform having a predetermined width of 10 ms or more. As a result, the rechargeable battery 14 is discharged with a pulse waveform as shown in FIG.

  In step S13, the CPU 10a refers to the outputs of the voltage sensor 11 and the current sensor 12, and measures the terminal voltage of the rechargeable battery 14 and the current flowing through the rechargeable battery 14 at a predetermined sampling period. For example, the RAM 10c Is stored as data 10ca. Regarding the current, the case where the rechargeable battery 14 is charged can be positive, and the case where it can be discharged can be negative.

  In step S14, the CPU 10a determines whether or not the measurement is completed. If it is determined that the measurement is completed (step S14: Y), the process proceeds to step S15, and otherwise (step S14: N). Returns to step S13 and repeats the same processing. In addition, the measurement process also including the measurement time before and after the pulse shown in FIG. 3 is performed by the process of step S12 to step S14.

  In step S15, the CPU 10a sets the pulse width of the pulse discharge to T2. For example, T2 is set to a predetermined value of 3 ms or less. Note that 3 ms is an example, and other values may be used.

  In step S16, the CPU 10a controls the discharge circuit 15 via the I / F 10e to discharge the rechargeable battery 14 at least once with a pulse waveform having a predetermined width of 3 ms or less. As a result, the rechargeable battery 14 is discharged with a pulse waveform as shown in FIG.

  In step S17, the CPU 10a refers to the outputs of the voltage sensor 11 and the current sensor 12, and measures the terminal voltage of the rechargeable battery 14 and the current flowing through the rechargeable battery 14 at a predetermined sampling period. For example, the RAM 10c Is stored as data 10ca.

  In step S18, the CPU 10a determines whether or not the measurement is completed. If it is determined that the measurement is completed (step S18: Y), the process proceeds to step S19, and otherwise (step S18: N). Returns to step S17 and repeats the same processing. In addition, the measurement process also including the measurement time before and after the pulse shown in FIG. 3 is performed by the process of step S16 to step S18.

  In step S19, the CPU 10a calculates the reaction resistance Rct1_1 based on the measurement result by pulse discharge. More specifically, the voltage and current obtained by the measurement by the discharge having the pulse width T1 are corrected by correcting the voltage and current measured in the time before and after the pulse discharge by the equations (1) to (4). The subsequent voltage and current are applied to equation (5) to determine the internal impedance Z. Next, the voltage and current obtained by the measurement with the discharge having the pulse width T2 are corrected by the equations (1) to (4), and the voltage and current measured in the time before and after the pulse discharge are corrected. The voltage and current are applied to Equation (5) to determine Rohm_1. Then, the value of the reaction resistance Rct1_1 is obtained by subtracting the conductor resistance / liquid resistance Rohm_1 from the internal impedance Z.

  In step S20, the CPU 10a calculates the reaction resistance Rct1_2 based on the measurement result by pulse discharge. More specifically, the voltage and current obtained by the measurement with the discharge having the pulse width T1 (without correcting the measured voltage and current in the time before and after the pulse by the equations (1) to (4)). The internal impedance Z is obtained by applying to Equation (5). Next, the voltage and current obtained by the measurement by the discharge with the pulse width of T2 are obtained (without correcting the measured voltage and current in the time before and after the pulse by the equations (1) to (4)), Apply to (5) to determine Rohm_2. Then, by subtracting the conductor resistance / liquid resistance Rohm_2 from the internal impedance Z, the value of the reaction resistance Rct1_2 is obtained.

  In Step S21, the CPU 10a corrects the reaction resistance Rct1_1 and the reaction resistance Rct1_2 obtained in Step S19 and Step S20 with the temperature. More specifically, the CPU 10 a refers to the output of the temperature sensor 13, measures the external temperature of the rechargeable battery 14, and applies the external temperature to the thermal equivalent model of the rechargeable battery 14, whereby the rechargeable battery 14 electrolyte temperature is estimated. Then, referring to a table (for example, a table stored in the ROM 10b) showing a correspondence relationship between the electrolytic solution temperature and the reaction resistance, the reaction resistance Rct1_1 and the reaction resistance are set so as to have values at a reference temperature (for example, 25 ° C.). The value of Rct1_2 is corrected.

  In Step S22, the CPU 10a corrects the reaction resistance Rct1_1 and the reaction resistance Rct1_2 obtained in Step S19 and Step S20 with the SOC. More specifically, for example, the CPU 10a obtains the current SOC from the relationship between the OCV and the SOC. Then, referring to a table (for example, a table stored in the ROM 10b) indicating the correspondence relationship between the SOC and the reaction resistance, the reaction resistance Rct1_1 and the reaction resistance Rct1_2 are set so as to have values in the standard SOC (for example, 100%). Correct the value.

  In step S23, the CPU 10a applies the values of the reaction resistance Rct1_1 and the reaction resistance Rct1_2 corrected by the temperature and the SOC in step S21 and step S22 to the above-described equation (6) to obtain ΔRct1.

  In step S24, the CPU 10a obtains the value of ΔSOC by applying the value of ΔRct1 obtained in step S23 to the above-described equation (7).

  In step S25, the CPU 10a obtains the value of the polarization voltage Vp by applying the value of ΔSOC obtained in step S24 to the above-described equation (8).

  According to the above processing, the polarization voltage Vp can be accurately obtained. Moreover, according to the above process, if the engine 17 is stopped, the polarization voltage can be estimated at an arbitrary timing.

(C) Description of Modified Embodiment It goes without saying that the above embodiment is merely an example, and the present invention is not limited to the case described above. For example, in the above embodiment, the reaction resistance Rct1_1 obtained by correcting the voltage and current during the pulse discharge by the equations (1) to (4) based on the voltage and current before and after the pulse discharge, and the equation ( Although the polarization voltage is obtained based on the reaction resistance Rct1_2 obtained without correction according to 1) to (4), for example, the polarization voltage may be obtained based on the following method.

  More specifically, the rechargeable battery 14 is pulse-discharged by the discharge circuit 15, the voltage drop from the voltage before the start of discharge is measured, and the value of the internal resistance is obtained by dividing this voltage drop by the current. Then, the coefficient is calculated by fitting the obtained internal resistance value with the function shown in the equation (9).

  R (tn) = Rct1_3 × (1-exp (−τ / tn)) + Rohm_3 (9)

  In equation (9), Rct1_3 is a reaction resistance, Rohm_3 is a conductor resistance / liquid resistance, τ is a time constant, and exp () is an exponential function indicating the power of the base e of the natural logarithm.

  FIG. 6 is a diagram showing the result of fitting according to equation (9). In FIG. 6, the horizontal axis indicates the elapsed time from the start of pulse discharge, and the vertical axis indicates R (tn) in Expression (9). In FIG. 6, a curve (fitted) indicates the result of fitting according to the equation (9), and a rectangle, a triangle, a circle, an American mark (meas), and the like indicate measurement results. In FIG. 6, various types of batteries were actually measured, but the fitting results and the measurement results are in good agreement.

  Next, ΔRct2 is obtained by the following equation (10).

  ΔRct2 = Rct1 — 3−Rct1 — 1 (10)

  Subsequently, ΔRct2 obtained by the equation (10) is applied to the following equation (11) to calculate ΔSOC which is a change amount of the SOC. J () is a predetermined function with ΔRct2 as a variable, and can be obtained by actual measurement, for example.

  ΔSOC = k (ΔRct2) (11)

  Next, the CPU 10a calculates the polarization voltage Vp based on the following equation (12) from ΔSOC obtained by the equation (11). Note that m () is a predetermined function with ΔSOC as a variable, and can be obtained by actual measurement, for example.

  Vp = m (ΔSOC) (12)

  In the above description, ΔRct2 is obtained based on the difference value between the reaction resistance Rct1_3 and the reaction resistance Rct1_1 shown in the equation (10). However, ΔRct2 is obtained based on a ratio thereof (for example, Rct1_3 / Rct1_1). May be. Similarly, in the above-described equation (6), ΔRct1 is obtained based on the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1. However, ΔRct1 is obtained based on the ratio (for example, Rct1_2 / Rct1_1). It may be. Further, the ratio of the difference between the reaction resistance Rct1_1 and the reaction resistance Rct1_2 and the conductor resistance / liquid resistance Rohm_1 (for example, (Rct1_2−Rct1_1) / Rohm_1) may be ΔRct1, and ΔSOC may be obtained based on this ΔRct1. Good.

  In the above description, ΔRct is obtained by a combination of Rct1_1 and Rct1_2 and Rct1_1 and Rct1_3. However, a difference or a ratio by any two of Rct1_1, Rct1_2, and Rct1_3 may be obtained. Good. Alternatively, a predetermined function based on any two combinations of Rct1_1, Rct1_2, and Rct1_3 (for example, ΔRct = f (Rct1_1, Rct1_2 in the case of two combinations of Rct1_1 and Rct1_2)) is obtained. You may do it.

  FIG. 7 is a diagram showing the relationship between the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1 and the SOC change amount during charging before Rct measurement. As shown in FIG. 7, it can be seen that there is a substantially linear relationship between the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1 and the SOC change amount at the time of charging before Rct measurement.

  FIG. 8 is a diagram showing the relationship between the ratio of the reaction resistance Rct1_2 and the reaction resistance Rct1_1 and the SOC change amount during charging before Rct measurement. As shown in FIG. 8, it can be seen that there is a substantially linear relationship between the ratio of the reaction resistance Rct1_2 to the reaction resistance Rct1_1 and the SOC change amount during charging before Rct measurement.

  FIG. 9 is a diagram illustrating a relationship between a value obtained by dividing the difference value between the reaction resistance Rct1_2 and the reaction resistance Rct1_1 by the conductor resistance / liquid resistance Rohm_1 and the SOC change amount during charging before Rct measurement. As shown in FIG. 9, there is a substantially linear relationship between the value obtained by dividing the difference between the reaction resistance Rct1_2 and the reaction resistance Rct1_1 by the conductor resistance / liquid resistance Rohm_1 and the SOC change amount at the time of charging before Rct measurement. I understand that

  FIG. 10 is a diagram showing the relationship between the ratio of the reaction resistance Rct1_3 and the reaction resistance Rct1_1 and the SOC change amount during charging before Rct measurement. As shown in FIG. 10, it can be seen that there is a substantially linear relationship in a certain region between the ratio of the reaction resistance Rct1_3 and the reaction resistance Rct1_1 and the SOC change amount at the time of charge before Rct measurement.

  In the above embodiment, the polarization voltage Vp is calculated by performing pulse discharge while the vehicle is stopped. For example, pulse discharge is performed at the timing when the polarization of the rechargeable battery 14 is eliminated. The obtained reaction resistance value may be stored as a reference value, and the polarization voltage Vp may be obtained based on a difference value or a ratio with the reaction resistance value obtained by performing pulse discharge at an arbitrary timing.

  More specifically, at the timing at which the polarization of the rechargeable battery 14 is eliminated (for example, the timing at which the engine 17 is stopped and a predetermined time (ten hours or more) has elapsed), the reaction resistance is generated by pulse discharge by the method described above. Rct1_1, Rct1_2, Rct1_3, and conductor resistance / liquid resistance Rohm are obtained, and these are stored as Rct1_1r, Rct1_2r, Rct1_3r, and Rohmr.

  Next, at an arbitrary timing, the reaction resistances Rct1_1, Rct1_2, Rct1_3, and the conductor resistance / liquid resistance Rohm are obtained by pulse discharge by the method described above, and these are stored as Rct1_1c, Rct1_2c, Rct1_3c, Rohmc.

  Next, ΔRatio_Rct1_1 is obtained based on the following formulas (13) to (15).

Ratio_Rct1_1 = Rct1_1c / Rct1_1r (13)
Ratio_Rct1_3 = Rct1_3c / Rct1_3r (14)
ΔRatio_Rct1_1 = Ratio_Rct1_1-Ratio_Rct1_3 (15)

  FIG. 11 is a diagram illustrating a relationship between Rct1_3 (and Rct1_1) and the SOC change amount at the time of charging before Rct1 measurement. As indicated by a solid line and a rectangle in FIG. 11, Rct1_3 increases approximately in proportion to the SOC change amount ΔSOC during charging. For this reason, based on the following formula | equation (16), SOC variation amount at the time of charge can be estimated from the increase rate of Rct1_3. Note that n () is a predetermined function, and can be obtained by actual measurement, for example.

  ΔSOC = n (Rct1_3) (16)

  Note that, as indicated by a broken line and a circle in FIG. 11, Rct1_1 also increases, but does not have a substantially proportional relationship as in Rct1_3, but changes according to the SOC change amount during charging. For this reason, based on the following formula | equation (17), SOC variation | change_quantity at the time of charge can be estimated from the increase rate of Rct1_1. Note that o () is a predetermined function, and can be obtained by actual measurement, for example.

  ΔSOC = o (Rct1_1) (17)

  FIG. 12 is a diagram showing the relationship between ΔRatio_Rct1_1 and the SOC change amount during charging before Rct1 measurement. As shown in FIG. 12, ΔRatio_Rct1_1 and the Rct1 pre-measurement SOC change amount have a substantially proportional relationship from the vicinity where ΔRatio_Rct1_1 exceeds 10%. For this reason, the SOC change amount at the time of charging can be estimated by the following formula (18) from ΔRatio_Rct1_1 (see formula (15)), which is the difference between the relative values of Rct1. Note that p () is a predetermined function, and can be obtained by actual measurement, for example.

  ΔSOC = p (ΔRatio_Rct1_1) (18)

  Moreover, the flowchart shown in FIG. 5 is an example, and the present invention is not limited only to the processing of these flowcharts.

  In the above embodiment, the width of the pulse waveform is T1 = 10 ms and T2 = 3 ms. However, other widths may be set.

  In the above embodiment, the case where the pulse discharge is performed once has been described as an example. However, the pulse discharge is performed twice or more, and the average value of the measured values in the two or more pulse discharges is obtained. Also good.

  Further, in the above embodiment, the polarization voltage of the rechargeable battery 14 is calculated based on the difference or ratio of the reaction resistances obtained by two different calculation methods. Is applied to a predetermined function (for example, ΔRct1 = q (Rct1_2, Rct1_1): q () is a predetermined function with Rct1_2 and Rct1_1 as variables, for example, a linear function of two variables). Alternatively, the polarization voltage may be obtained.

  In the above embodiment, the reaction resistance value is corrected based on the temperature and SOC in the reference state. However, the open circuit voltage (OCV) may be corrected to the reaction resistance value in the reference state. That is, the reaction resistance value in at least one reference state of temperature, SOC, and OCV may be corrected.

DESCRIPTION OF SYMBOLS 1 Chargeable battery state detection apparatus 10 Control part 10a CPU
10b ROM
10c RAM
10d Communication unit 10e I / F
DESCRIPTION OF SYMBOLS 11 Voltage sensor 12 Current sensor 13 Temperature sensor 14 Chargeable battery 15 Discharge circuit 16 Alternator 17 Engine 18 Starter motor 19 Load

Claims (7)

In the rechargeable battery state detection device that detects the state of the rechargeable battery,
Discharging means for pulse discharging the rechargeable battery;
Measuring means for measuring the voltage value and current value during or before and after the pulse discharge by the discharging means;
First calculation means for calculating a value of a predetermined circuit element constituting an equivalent circuit of the rechargeable battery by a first calculation method based on the voltage value and the current value measured by the measurement means;
A second calculation for calculating a value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured by the measurement means. Means,
Polarization of the rechargeable battery based on a difference, a ratio, or a value obtained by applying the value of the circuit element to a predetermined function calculated by the first calculation means and the second calculation means A calculating means for calculating a voltage;
A rechargeable battery state detection device comprising:   The rechargeable battery state detection device according to claim 1, wherein the circuit element to be calculated by the first calculation unit and the second calculation unit is a reaction resistance or a charge transfer resistance. The first calculation means and the second calculation means are:
(1) From the value obtained by dividing the voltage value during discharge when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1, by a rectangular pulse having a pulse width of T2 (<T1) A calculation method in which the value obtained by subtracting the value obtained by dividing the voltage value during discharge by the current value when discharged is the value of the reaction resistance,
(2) A corrected voltage value obtained by correcting a voltage value and a current value during discharge when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1 with a voltage value and a current value before and after the discharge, respectively. After correction by correcting the voltage value and current value during discharge when the discharge is performed by a rectangular pulse with a pulse width of T2 (<T1) from the value obtained by dividing by the value, using the voltage value and current value before and after the discharge, respectively. A calculation method in which the value obtained by subtracting the value obtained by dividing the voltage value by the corrected current value is the value of the reaction resistance,
(3) The reaction resistance and the conductor resistance / liquid resistance are included as coefficients by a plurality of values obtained by dividing the voltage drop value during discharge from the start of discharge when the rechargeable battery is pulse-discharged by the current value. A calculation method for fitting a predetermined mathematical formula and obtaining a reaction resistance value from a coefficient value;
Any two of the calculation methods (1) to (3) are used.
The rechargeable battery state detection device according to claim 1 or 2, characterized by the above-mentioned.   The rechargeable battery state detection device according to claim 3, wherein the first calculation unit and the second calculation unit use the calculation method (1) and the calculation method (2), respectively. In the calculation method of (1) and the calculation method of (2), the first calculation means and the second calculation means are discharging when the rechargeable battery is discharged by a rectangular pulse having a pulse width of T1. Instead of the value obtained by dividing the voltage value of the current by the current value, the voltage value during discharge when the pulse is discharged by the rectangular pulse having a pulse width of T2 (<T1) is replaced with the value obtained by dividing by the current value The value of the reaction resistance is obtained by subtracting the value of the conductor resistance / liquid resistance obtained by the calculation method of (3).
The rechargeable battery state detection device according to claim 4.   The reaction resistance value obtained by the first calculation means and the second calculation means is corrected so that at least one of temperature, charging rate (SOC), and open circuit voltage (OCV) is a value in a predetermined reference state. The rechargeable battery state detection device according to any one of claims 1 to 5. In the rechargeable battery state detection method for detecting the state of the rechargeable battery,
A discharging step of pulse discharging the rechargeable battery;
A measurement step of measuring a voltage value and a current value during or before the pulse discharge in the discharge step;
A first calculation step of calculating a value of a predetermined circuit element constituting the equivalent circuit of the rechargeable battery by a first calculation method based on the voltage value and the current value measured in the measurement step;
A second calculation for calculating a predetermined circuit element constituting a value of the equivalent circuit of the rechargeable battery by a second calculation method different from the first calculation method based on the voltage value and the current value measured in the measurement step. Steps,
Polarization of the rechargeable battery based on a difference, ratio, or value obtained by applying the value of the circuit element to a predetermined function calculated in the first calculation step and the second calculation step A calculation step for calculating a voltage;
A rechargeable battery state detection method characterized by comprising:

Images